The invention relates to a device for the actuation of a throttle valve, in particular a throttle valve of an intake system of an internal combustion engine, by means of a servomotor and to an internal combustion engine having the device for the actuation of the throttle valve.
For the actuation of throttle valves of internal combustion engines, conventional devices use servomotors which are coupled in torque-transmitting fashion to the shaft of the respective throttle valve. A problem here is that the medium stream that is controlled by the throttle valve is at a high temperature in the case of supercharged engines or internal combustion engines, whereas conventional servomotors however tolerate only low levels of thermal heating. The use of servomotors that can withstand high thermal loads would be one conceivable measure to solve said problem. Special servomotors with very high thermal load capability would however be very cumbersome and would thus also entail correspondingly high cost outlay.
To be able to use conventional servomotors to actuate throttle valves that are used to control a medium stream at very high temperature, it would be possible to implement measures for realizing thermal decoupling between the throttle valve and servomotor. DE 103 44 218 A1 discloses thermal decoupling between a servomotor and a valve. For this purpose, use is made of a coupling element in the form of a rocker arm, which coupling element is composed of a material which exhibits poor thermal conductivity. Such a rocker arm is however not suitable for transmitting torque between the shaft of a servomotor and the shaft of a throttle valve.